You will need to be invited to join Depop Payments currently and once you have been invited, you will be able to signup from:
Settings > Preferences > Depop Payments.
To signup you will need to add some personal information including your bank account when signing up. The information required differs by country and whether verification checks have been successful.
Our payment processing partner Stripe may require additional information to verify your identity. We will refer you to a secure Stripe form to input these details.